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United States Patent | 5,671,154 |
Iizuka ,   et al. | September 23, 1997 |
In an ultrasonic inspection apparatus for detecting a flaw present in a target object (2) on the basis of an echo signal (b) from the target object (2), a high-frequency echo signal (b) output from an ultrasonic transmit-receive unit (1) is A/D-converted at a high sampling frequency (f.sub.S) in only a predetermined measurement time interval (T.sub.M) in a repetitive period (T.sub.O) of an ultrasonic pulse (a) and is temporarily stored in a storage unit (12). Thereafter, the sampling data is read out at a read frequency (f.sub.R) lower than the sampling frequency (f.sub.S). A digital signal process for noise reduction using a first digital filter (18) or a synchronous adding/averaging circuit (27) is performed to only data in the measurement time interval (T.sub.M). As a result, noise included in the echo signal (b) is considerably reduced while on-line inspection is kept performed.
Inventors: | Iizuka; Yukinori (Tokyo, JP); Horigome; Hidekazu (Tokyo, JP); Murayama; Akira (Tokyo, JP); Nakazawa; Shin (Tokyo, JP) |
Assignee: | NKK Corporation (Tokyo, JP) |
Appl. No.: | 374777 |
Filed: | January 26, 1995 |
PCT Filed: | June 7, 1994 |
PCT NO: | PCT/JP94/00916 |
371 Date: | January 26, 1995 |
102(e) Date: | January 26, 1995 |
PCT PUB.NO.: | WO94/29714 |
PCT PUB. Date: | December 22, 1994 |
Jun 07, 1993[JP] | 5-135562 |
Current U.S. Class: | 702/39; 73/600; 73/602; 73/609; 73/610; 73/614 |
Intern'l Class: | G01N 029/04; G01N 029/10 |
Field of Search: | 73/592,599,600,602,609,610,611,613,614,615,632,634 364/506,507,550,551.01,572,574,575 |
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